The objectives of this proposal are two: 1) to further study the effects of the drug ethacrynic acid (EA) on the ear and 2) to clarify some aspects of basic activity within the stria vascularis. (1) It is proposed to study in more detail the capillary stasis which we have found in our guinea pigs sacrificed at 2 days after a 40 mg/Kg dose of EA. (2) We will examine in more detail changes which occur in other cell groups besides the stria and also determine if further degeneration occurs at periods later than one week, all after a single, large dose of EA. (3) We will study the effects of small, daily doses of EA given over a 10 day period, on the stria vascularis and sensory cells. (4) We will examine the changes that occur in the cell surface coat after EA, and determine if desialization of the strial cells in normal animals has any effect on the endocochlear potential. The studies will be made by use of ordinary light as well as electron microscopy and correlated with measurements of the DC endocochlear potentials, and the AC cochlear potentials.